1. Field of the Invention
The invention relates to a safety mechanism for elevator systems. The invention also relates to a method for operating the safety mechanism in accordance with the invention.
2. Background Information
The elevator cars, as well as the elevator shaft of elevator systems which meet modern safety requirements are customarily provided with automatically operable sliding doors. Depending on the size of the door opening, these can be single- or multi-panel individual sliding doors, or centrally opening double sliding doors. In various elevator systems, the different door types can also be combined with each other. While the closing process of automatic sliding doors generally no longer poses problems, since closing force limiters are usually provided, a large potential for improvement continues to exist in regard to the opening process. The problematic area with automatically opening sliding doors lies in particular at the pinching edge between the surface of the door panel and the door jamb. With multi-panel sliding doors there are additionally analogous pinching edges between the surface of the respective door panel and the front edge of the further panel element adjoining it in the direction of the door jamb.
The sliding doors of known elevator systems pose a definite risk that an object leaning against the sliding door, or even a part of a body of a person leaning against the sliding door, will be taken along by the automatically opening sliding door and be pinched. In connection with children in particular there is the chance that, because of a certain play instinct, they press their palms against the door panel. In connection with doors of chromium steel, such as were mainly used as sliding doors of elevators in the past, this hardly posed a danger because of the low coefficient of friction. However, glass sliding doors have been increasingly employed in connection with elevators in the last few years. Because of the unobstructed view of the operation of the elevator from the outside, sliding glass doors have a magical attraction for people, and particularly children. But the coefficient of friction between glass and the skin is relatively large. Moisture, for example sweat, on the skin additionally increases the adhesion of the skin to the glass surface. Because of this, the hand can be pulled along with the opening glass door and can be pinched at the pinching edge. This can lead to injury when it is attempted to release the hand.
It is therefore desirable to monitor the pinching edges at the automatic sliding doors of the elevator car and in the elevator shafts. To this end, presence sensors should be provided at all pinching edges of the elevator car and all pinching edges at the elevator shaft doors on all floors. In this connection the fact that the sliding doors on the elevator shaft are generally passive doors should be taken into consideration. This means that the elevator shaft doors of the respective floors can only be automatically opened together with the sliding door of the elevator car stopped in front of them. Customarily the drive mechanism for the sliding doors of the elevator car are located on the roof of the car. Appropriately embodied engagement elements on the sliding doors of the elevator car take care of opening the elevator shaft doors. A difficulty in the conversion of a system with a number of presence sensors lies, for example, in routing the signal of the elevator shaft door in front of which the elevator car is stopped to the elevator car so that, when required, the door opening mechanism can be changed to a slow opening mode or interrupted. Additional problems are posed by the logical linkage of the presence sensors, so that a correct operation of the elevator system is preserved. The multitude of sensors and the outlay to be expected have probably led in the past to the non-use of such elaborate safety mechanisms in connection with known elevator systems.